Improvement in grinding-mills



' llNrrnn Sr,Ai-slitsv PATENT GEoEGE sELsoR, orf PHiLAEEErm-A,EEN-ssrtvanm,

'IMPROVEMENT IN GRlNDlNG-MILLS.

Specification forming part of Letters Patent No. l 12,080, datedFebruary 21, 1871.

.To @ZZ whom it may concerns:

Be 1t known that I, GEORGE SELscR, of Philadelphia, county ofPhiladelphia, State of Pennsylvania, have invented an ImprovedGrinding-Mill, of which the following is a specification.

My invention consists of a grinding-mill, too fully describedhereinafter to need preliminary explanation, the object of my inventionbeing simplicity as regards construction and increased grindingefficiency.

In the accompanying drawings, Figure lis a vertical section of the shelland burr of my improved grinding-mill; Fig. 2, an inverted plan view,showing the lower face of the burr; Fig. 3, a plan view of the lowerportion of the shell; Fig. 4, an inverted plan view of the upper portionof the shell, and Fig. 5 a plan view of the upper portion of the burr.

The sheet A is composed of the two portions a. and c', inclined incontrary directions, and flanged at their outer edges for attachment toeach other by suitable screws or other appropriate fastenings.

The burr B has two grindingsurfaces in clined in contrary directions,one surface, b, conforming, or nearly so, in its inclination to that ofthe upper portion, a, of the shell, and the other surface, d, to thelower portion of the same. Ihe burr is rendered adjustable within theshell, in the presentlinstance, by a setscrew, l), on the point of whichthe burr re volves, the screw passing through a yoke, f, attached to orforming a part of the lower portion of the shell.

Either cast with or secured to the burr is a spindle, E, adapted to abearing, e, supported by lugs ff, connected to the upper portion, a, ofthe shell.

It will be seen on reference to Figs. 4 and 5 that the uppergrinding-surface of the burr and that of the upper portion, c, of4 theshell have a comparatively coarse dress, while the lowergrinding-surfaces of both shell and burr have a much finer dress. Inother words, the material to be groundncoffee, for instance-is brokenand crushed by being subjected to the upper grinding -surfaces, butafter passing thence to the lower grinders the latter triturate thecrushedfpieces to the desired degree of fineness.

I have found, after repeated tests, that coffee and other substances canbe ground much faster by this duplex operation than in ordinary mills. i

One of the most important features of my invention, however, is thereadiness with which the burr can be adjusted to grind eoarser or iinerwithout impairing the t,elfect of either grindingsurfaees. By loweringthe burr, for instance, finer grinding will be insured without in anyway detracting from the effective crushing properties of the uppergrinding-surfaces. Another advantage of my invention is the economy withwhich it can be carried out. The two portions of the shell, forinstance, admit of being easily cast and se= cured together, and if itbe desirable to make them of steel they can be easily formed by andbetween suitable dies and the same may be said of the burr, which can,with its dress, be swaged to the desired shape. It is when the mill ismade of cast-iron, however, that its simplicity beeolnes mostapparent,the upper portion of the shell and bearing for the spindle, being eastin one piece, so that the necessity of a cross-piece for supporting theupper end of the spindle is avoided, and the lower portion of the shellhaving cast on it the yoke for carrying the screw for adjusting andsupporting the burr.

In Fig. l, I have shown the mill as adaptedto coffee-grinding, thedotted lines y designating [the hopper for receiving the coffe, and thedotted lines :v the top of the box which contains the drawer forreceiving the ground coffee. It will be seen that the mill is secured tothetop of the box by the same screws or bolts by which the two portionsof the shell are connected together.

Either the upper or lower grinding-surfaces, or both, of the burr may beslightly curved without departing from the main feature of my invention,the surfaces of the shell having a corresponding or nearly correspondingcurve.

I claiml. The combination, in a grinding-mill, of a burr having twoinclined grinding-surfaces, one coarser than the other, and a shell withtwo inclined grinding-surfaces, the whole being arranged, substantiallyas described, so

that the material operated on, after being1 In testimony whereof I havesigned my broken by passing over one surface of the name to thisspecification in the presence of burr, shall be further reduced inContact with two subscribing witnesses.

the other grinding-surface, as set forth.

2. The combination of 'the shell A, having l two inclinedgrinding-surfaces and arranged horizontally, and a Vertical spindle, E,ad- I justed by a set-screw, D, or its equivalent,a11d NVM. A, STEEL,

Carrying a double-inclined horizontal burr, B, FRANKLIN B. RICHARDS. asset forth. I I

GEORGE SLSOR.

YVitnesses:

